Re: [PATCH v8 00/18] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs

John Garry
2020-09-04T09:12:16Z

On 03/09/2020 22:23, Jens Axboe wrote:
> On 8/19/20 9:20 AM, John Garry wrote:
>> Hi all,
>>
>> Here is v8 of the patchset.
>>
>> In this version of the series, we keep the shared sbitmap for driver tags,
>> and introduce changes to fix up the tag budgeting across request queues.
>> We also have a change to count requests per-hctx for when an elevator is
>> enabled, as an optimisation. I also dropped the debugfs changes - more on
>> that below.
>>
>> Some performance figures:
>>
>> Using 12x SAS SSDs on hisi_sas v3 hw. mq-deadline results are included,
>> but it is not always an appropriate scheduler to use.
>>
>> Tag depth 4000 (default) 260**
>>
>> Baseline (v5.9-rc1):
>> none sched: 2094K IOPS 513K
>> mq-deadline sched: 2145K IOPS 1336K
>>
>> Final, host_tagset=0 in LLDD *, ***:
>> none sched: 2120K IOPS 550K
>> mq-deadline sched: 2121K IOPS 1309K
>>
>> Final ***:
>> none sched: 2132K IOPS 1185
>> mq-deadline sched: 2145K IOPS 2097
>>
>> * this is relevant as this is the performance in supporting but not
>> enabling the feature
>> ** depth=260 is relevant as some point where we are regularly waiting for
>> tags to be available. Figures were are a bit unstable here.
>> *** Included "[PATCH V4] scsi: core: only re-run queue in
>> scsi_end_request() if device queue is busy"
>>
>> A copy of the patches can be found here:
>> https://github.com/hisilicon/kernel-dev/tree/private-topic-blk-mq-shared-tags-v8
>>
>> The hpsa patch depends on:
>> https://lore.kernel.org/linux-scsi/20200430131904.5847-1-hare@suse.de/
>>
>> And the smartpqi patch is not to be accepted.
>>
>> Comments (and testing) welcome, thanks!
>
> I applied 1-11, leaving the SCSI core bits and drivers to Martin. I can
> also carry them, just let me know.
>

Great, thanks!

So the SCSI parts depend on the block parts for building, so I guess it
makes sense if you could carry them also.

hpsa and smartpqi patches are pending for now, but the rest could be
picked up. Martin/James may want more review of the SCSI core bits, though.

Thanks again,
John